the crested gene

[bock]

I do not plan on breeding crested ducks, but I am curious about how the crested gene is passed. My understanding is that two crested birds should never be bred together because most of them will inherit a deadly gene. Is that true? And if you breed one crested duck to a non-crested duck, some will inherit the deadly gene, and x%will be crested and x% will be non-crested. So if I have this right, if I were to breed a white crested duck to say a Welsh Harlequin drake, would some end up crested, even though they are two different breeds? I was just curious, so thanks ahead of time for helping clear this up for me!

 

[duckyfromoz]

You pretty much have it on track. If both parent pass on the crested gene- then the duckling will not survive to hatch. If only one parent passes on a crested gene then the average ratio is - 25 % will not survive to hatch, 50 % will have crests, and 25% will not have crests. The gene is incompletely dominant - so does not always get passed onto offspring. As far as breeding a white crested to a WH - yes some could end up crested despite the breed difference - depending on if the gene was passed on.

 

[rollyard]

The gene for "crested" is an incompletely dominant autosome. Two doses are reported to be lethal ie birds pure for the gene fail to hatch, so any crested birds seen are heterozygotes (Cr/cr+). It also reportedly exhibits expresses quite variably (both homozygotes & heterozygotes), with some heterozygotes appearing normal yet still carrying the gene. Two heterozygotes (crested) bred together will produce approx 25% lethal progeny which are pure for crested, 50% progeny impure (heterozygotes) ie crested, & 25% that don't carry the gene @ all. Crested to non-crested will produce approx 50% crested heterozygotes (Cr/cr+) & 50% non-crested homozygotes (cr+/cr+) progeny. Doesn't matter what the breed is.

 

[bock]

Thanks! I have read bits and pieces about it over the years, but I was just wondering if I had it right.